Increasing incidents of cyber attacks and evolution of quantum computing poses challenges to secure existing information and communication technologies infrastructure. In recent years, quantum key distribution (QKD) is being extensively researched, and is widely accepted as a promising technology to realize secure networks. Optical fiber networks carry a huge amount of information, and are widely deployed around the world in the backbone terrestrial, submarine, metro, and access networks. Thus, instead of using separate dark fibers for quantum communication, integration of QKD with the existing classical optical networks has been proposed as a cost-efficient solution, however, this integration introduces new research challenges. In this paper, we do a comprehensive survey of the state-of-the-art QKD secured optical networks, which is going to shape communication networks in the coming decades. We elucidate the methods and protocols used in QKD secured optical networks, and describe the process of key establishment. Various methods proposed in the literature to address the networking challenges in QKD secured optical networks, specifically, routing, wavelength and time-slot allocation (RWTA), resiliency, trusted repeater node (TRN) placement, QKD for multicast service, and quantum key recycling are described and compared in detail. This survey begins with the introduction to QKD and its advantages over conventional encryption methods. Thereafter, an overview of QKD is given including quantum bits, basic QKD system, QKD schemes and protocol families along with the detailed description of QKD process based on the Bennett and Brassard-84 (BB84) protocol as it is the most widely used QKD protocol in the literature. QKD system are also prone to some specific types of attacks, hence, we describe the types of quantum hacking attacks on the QKD system along with the methods used to prevent them. Subsequently, the process of point-to-point mechanism of QKD over an optical fiber link is described in detail using the BB84 protocol. Different architectures of QKD secured optical networks are described next. Finally, major findings from this comprehensive survey are summarized with highlighting open issues and challenges in QKD secured optical networks.
Increasing incidents of cyber attacks and evolution of quantum computing poses challenges to secure existing information and communication technologies infrastructure. In recent years, quantum key distribution (QKD) is being extensively researched, and is widely accepted as a promising technology to realize secure networks. Optical fiber networks carry a huge amount of information, and are widely deployed around the world in the backbone terrestrial, submarine, metro, and access networks. Thus, instead of using separate dark fibers for quantum communication, integration of QKD with the existing classical optical networks has been proposed as a cost-efficient solution, however, this integration introduces new research challenges. In this paper, we do a comprehensive survey of the state-of-the-art QKD secured optical networks, which is going to shape communication networks in the coming decades. We elucidate the methods and protocols used in QKD secured optical networks, and describe the process of key establishment. Various methods proposed in the literature to address the networking challenges in QKD secured optical networks, specifically, routing, wavelength and time-slot allocation (RWTA), resiliency, trusted repeater node (TRN) placement, QKD for multicast service, and quantum key recycling are described and compared in detail. This survey begins with the introduction to QKD and its advantages over conventional encryption methods. Thereafter, an overview of QKD is given including quantum bits, basic QKD system, QKD schemes and protocol families along with the detailed description of QKD process based on the Bennett and Brassard-84 (BB84) protocol as it is the most widely used QKD protocol in the literature. QKD system are also prone to some specific types of attacks, hence, we describe the types of quantum hacking attacks on the QKD system along with the methods used to prevent them. Subsequently, the process of point-to-point mechanism of QKD over an optical fiber link is described in detail using the BB84 protocol. Different architectures of QKD secured optical networks are described next. Finally, major findings from this comprehensive survey are summarized with highlighting open issues and challenges in QKD secured optical networks.
Quantum Key Distribution (QKD) is a mechanism for ensuring secure key exchange based on the fundamental principles of quantum mechanics. It has evolved significantly over the past four decades. QKD networks have evolved from experiments to large-scale deployments, enabling longer transmission distances and enhanced security performance. Existing information security relies on modern cryptographic primitives such as Elliptic Curve Diffie–Hellman (ECDH), RSA, and AES. Although AES-256 is considered quantum-resistant, ECDH and RSA cannot withstand attacks by a specific quantum computer. Specifically, with enough quantum bits, Shor’s and Grover’s algorithms can break RSA and ECDH through rapid integer factorization and quantum search capabilities, respectively. Consequently, QKD offers a promising method towards information-theoretic security, using trusted nodes, optical routers, and future quantum repeaters. However, completely replacing current infrastructure with QKD systems is both costly and impractical. Thus, existing QKD can be integrated into current infrastructure, including dark fiber and satellite systems. Previous surveys have primarily focused on isolated aspects such as fiber-based QKD, free-space QKD, or theoretical Internet architectures. There is a lack of a comprehensive survey that simultaneously presents fundamentals, QKD protocols and security, network implementations, and experimental advances. This makes it difficult for readers to grasp the full scope of the field. This survey focuses on QKD from the ground up, covering the essential foundations of QKD, exploring various QKD protocols, concerning different types of attacks, reviewing real-world QKD network deployments, and highlighting challenges and future directions.
Quantum Key Distribution (QKD) constitutes one of the most profound practical applications of quantum mechanics, enabling two parties to exchange cryptographic keys whose security is guaranteed by the fundamental laws of physics rather than the assumed computational hardness of mathematical problems. As quantum computing capabilities continue to advance, classical public-key infrastructure faces an existential threat, rendering QKD a critical component of post-quantum secure communication architectures. This paper presents a comprehensive survey of QKD spanning foundational protocols, rigorous security proofs, hardware implementation challenges, deployment experiences across metropolitan fiber networks, and recent satellite-based experiments. We analyze the BB84, E91, B92, SARG04, continuous-variable, measurement-device-independent (MDI-QKD), and twin-field (TF-QKD) protocols in depth, examining their security assumptions, achievable key rates, and practical limitations. Particular attention is given to side-channel vulnerabilities in realistic implementations, decoy-state methods for mitigating photon-number-splitting attacks, and finite-key security analysis. We review key performance benchmarks from commercial systems and discuss integration with classical network infrastructure. The paper concludes by identifying open challenges in quantum repeater development, satellite QKD scalability, and standardization efforts essential for large-scale deployment.
As the limitations of classical cryptographic systems become increasingly evident in the face of advancing quantum algorithms, Quantum Key Distribution (QKD) emerges as a vital paradigm for securing information in next-generation networks. This paper explores the theoretical foundations and protocol architectures underpinning QKD, including BB84, E91, and newer hybrid approaches designed for scalable integration into existing infrastructures. Performance metrics such as key generation rate, error thresholds, and resistance to various attack models are critically examined across both fiber-optic and free-space implementations. Furthermore, the study delves into real-world deployment challenges—ranging from synchronization errors and quantum channel noise to cost-efficiency and interoperability with classical systems. By offering a comparative analysis and proposing optimization strategies, this work aims to pave the way for robust quantum-secure communication protocols suited for large-scale, heterogeneous network environments.
Quantum Key Distribution (QKD) protocols offer a revolutionary approach to secure communication, leveraging the principles of quantum mechanics to enable theoretically unbreakable encryption. This comprehensive review examines the security and efficiency of various QKD protocols, including BB84, E91, and Continuous Variable QKD. We analyze the fundamental principles underpinning these protocols, their implementation challenges, and the practical considerations for real-world deployment. Special emphasis is placed on the security proofs of QKD, addressing potential vulnerabilities such as photon number splitting attacks and detector blinding attacks. Additionally, we explore the efficiency of QKD systems in terms of key generation rates, distance limitations, and integration with existing communication infrastructures. Recent advancements in QKD technology, including satellite-based QKD and quantum repeaters, are also discussed. Our findings highlight the critical role of QKD in future-proofing communication security and the ongoing efforts to enhance its practicality and scalability. This review aims to provide a detailed understanding of the current state of QKD protocols, offering insights into their potential to transform secure communications in the quantum era.
A quantum key distribution (QKD) network is proposed to allow QKD protocols to be the infrastructure of the Internet for distributing unconditional security keys instead of existing public-key cryptography based on computationally complex mathematical problems. Numerous countries and research institutes have invested enormous resources to execute correlation studies on QKD networks. Thus, in this study, we surveyed existing QKD network studies and practical field experiments to summarize the research results (e.g., type and architecture of QKD networks, key generating rate, maximum communication distance, and routing protocol). Furthermore, we highlight the three challenges and future research issues in the security of QKD networks and then provide some feasible resolution strategies for these challenges.
As wireless networks become increasingly integral to modern communication infrastructures, the need for robust security mechanisms to protect sensitive information has never been more critical. Quantum Key Distribution (QKD) presents a revolutionary approach to secure communications by leveraging the principles of quantum mechanics to ensure the theoretical unbreakability of cryptographic keys. This study provides a comprehensive review of the current status of QKD technologies within the context of wireless networks, utilizing secondary data sources to analyze recent advancements, implementations, and challenges. The paper begins by outlining the fundamental principles of QKD and its superiority over classical cryptographic methods. It then examines recent developments in QKD protocols and their adaptability to wireless environments, highlighting successful case studies and experimental trials. Key challenges, including technological limitations, integration hurdles with existing network infrastructures, and cost considerations, are discussed in detail. The review also explores emerging trends and innovations, such as hybrid QKD systems and satellite-based implementations, which promise to expand the applicability and feasibility of QKD in wireless networks. Finally, the study delineates future prospects and potential research directions, emphasizing the need for interdisciplinary collaboration to overcome existing limitations and fully realize the potential of QKD in enhancing wireless network security.